Communicable Diseases and Plant Defenses

Communicable Diseases

• Communicable diseases are illnesses caused by pathogens (disease-causing agents) that can be transmitted from one organism to another.
• Examples include influenza, HIV, and tuberculosis.
• Transmission routes include direct contact, airborne droplets, vectors (e.g., mosquitoes), and contaminated food or water.
• Pathogens can be viruses, bacteria, fungi, or parasites.
• Communicable diseases can range from mild symptoms to severe illness and death.
• Prevention strategies include hygiene practices, vaccination, and quarantine measures.

Plant Defences

• Plants have evolved complex defence mechanisms to combat pathogens and herbivores.
• These defences are categorized as physical, chemical, and biological.
• Physical defences include tough outer layers (e.g., bark, waxy cuticle), thorns, and prickles that deter herbivores.
• Chemical defences involve producing toxins or secondary metabolites that are harmful or unpalatable to pests. Examples include alkaloids, tannins, and terpenes.
• Biological defences can involve attracting natural enemies (e.g., predators or parasites) of herbivores, or producing proteins that interfere with the growth or survival of pathogens.

Non-Specific Defences

• Non-specific defenses (innate immunity) are the first line of defense against pathogens, in both plants and animals.
• In animals, defenses include the skin, mucous membranes, and secretions like saliva and tears containing antimicrobial substances.
• The inflammatory response is a crucial non-specific defense mechanism, characterized by redness, swelling, heat, and pain.
• Complement proteins identify pathogens and signal immune responses.
• Some non-specific responses involve phagocytes (e.g., neutrophils and macrophages) that engulf and destroy pathogens through phagocytosis.
• In plants, physical barriers like cell walls, and antimicrobial compounds produced in response to infection, are part of the non-specific defense.

Monoclonal Antibodies

• Monoclonal antibodies are laboratory-produced antibodies.
• They are identical copies of the same antibody, targeting a single antigen.
• Monoclonal antibodies are generated by fusing a B cell (producing the antibody) with a myeloma cell (cancerous white blood cell line).
• Monoclonal antibodies are used in medicine for diagnostic tests and treating illnesses.
• They bind to specific targets (antigens) on pathogens or cancer cells.
• Monoclonal antibody therapies are becoming increasingly important in cancer treatment, autoimmune disorders, and other conditions requiring targeted therapy.
• Targeted therapy minimizes side effects compared to general treatments.